The present invention relates to a vehicle communication, tracking and security system, which utilizes a communication link over a cellular network to simultaneously transmit both voice and GPS vehicle location data.
Since the early part of this century, the automobile has become a major part of the culture both in the U.S. and throughout the world. The independence, freedom, and rapid travel that automobiles provide, however, has also resulted in an individual becoming lost, involved in accidents, and becoming victims of crime. By way of specific example of the latter, when an individual traveling in a vehicle experiences mechanical failure, they encounter a potentially dangerous situation because of the high crime rate in an area or unfortunate random acts of violence which occur upon the freeway and road systems. Likewise, vehicle theft is an ever-increasing problem with vehicles being stolen for personal use or parts. A new criminal trend has recently emerged known as carjacking wherein a vehicle is physically taken while being operated.
The prior art includes a number of systems that allow a vehicle""s occupant to obtain assistance if such assistance is needed, or to track the vehicle in the event of theft. See, e.g. U.S. Pat. No. 5,043,736 to Darnell, et al., U.S. Pat. No. 5,223,844 to Mansell, et al., U.S. Pat. No. 5,557,254 to Johnson, et al. These systems all share the same basic concept, that is, placing global positioning system (hereinafter GPS) in a vehicle to transmit the received GPS signals from the vehicle to a monitoring center over a cellular telephone link or pager system network. These systems are comprised of various components. Some have a GPS receiver located in the vehicle. The GPS receiver obtains GPS signals from satellites in orbit around the earth and, upon obtaining these signals, uses signal processing techniques to determine the GPS receiver""s location. Also located in the vehicle is a communication device to transmit the GPS signal from the vehicle. These communication devices include cellular transmission systems, pager systems or radios. Finally, a base center or monitoring center receives the GPS signal from the vehicle, and processes the information to determine the position of the vehicle. However, each of these prior art systems has significant drawbacks relating to both the manner in which they provide verbal communication between the operator of the vehicle and the monitoring center and the manner in which the GPS data is transmitted between the automobile and the monitoring center.
The present invention provides a significantly improved system that integrates the communication capabilities of a cellular telephone system with the geographic locating capabilities of Global Positioning Systems (GPS). The two technologies are mated in a vehicle tracking and communication system providing for simultaneous transmission of voice and data such that an operator of a vehicle may maintain continual voice communication with a monitoring center with the GPS processor and/or vehicle sensors simultaneously transmitting data to the monitoring center.
In particular, the invention comprises a single system, which, for ease of explanation, is discussed in two separate segments. The two segments communicate over a cellular telephone link. The first segment of the invention is in a vehicle. The first segment includes a mobile unit, cellular telephone componentry and optional vehicle sensors and optional remote operation devices.
The mobile unit contains a GPS receiver that continually obtains information from GPS satellites in orbit around the earth. These satellites transmit information which, when received and processed, provides the geographic location of the unit receiving the signals. Based on this information, a vehicle""s position is determined.
In addition to GPS location data, the vehicle""s sensor devices provide data to the communication device. The vehicle sensors monitor the vehicle for various occurrences such as break-in, theft, towing, accident, excessive distance traveled, user controlled speed violations, geographic boundary violations, or conversation monitoring. Data indicating the occurrence of an event combines with the voice signal.
Upon receiving and processing the mobile unit data (GPS location data and/or the sensor device data), a digital signal processor (DSP) combines the mobile unit data with a vehicle occupant""s voice signal, if present. If the telephone is not receiving voice data, the mobile unit data is sent alone.
The cellular telephone transmits the combined signal over the cellular telephone network to the second segment of the invention, the monitoring center. During the call to the monitoring center, the GPS receiver continuously provides GPS data to the signal processor for insertion into the outgoing signal.
The monitoring center has a communication device similar to the mobile unit, absent the GPS receiver; a telephone; a computer with tracking software and digitized maps, and a computer display to provide a visual representation of the map and the vehicle""s location thereon.
An incoming call undergoes a filtering process by a monitoring center DSP to separate the mobile unit data from the voice portion of the signal. The electronics route the voice portion of the signal to the telephone so that an operator or multiple operators at the monitoring center may converse with the vehicle""s occupants. The electronics route the data portions of the signal to the computer. The computer, in conjunction with the software and digitized maps, process the data to display a graphical representation of a map and the vehicle""s location thereon. Since the GPS data is continually and simultaneously being sent during the call, the operator at the monitoring center is able to track the movement of the vehicle during the conversation. The computer also displays vehicle sensor data.
In addition to verbal communication, in one embodiment of the invention, the monitoring center actually controls the vehicle""s remote operation devices with the computer. For example, the monitoring center can automatically stop operation of the vehicle""s engine, honk the horn, turn the lights on, or start the car to charge the battery. The monitoring center""s DSP filters and combines the voice of the monitoring center operator with data information from the computer. The monitoring center operator is thus able to provide directions or other information to the vehicle""s operator or occupants, and control the remote operation devices.
Advantageously, the claimed invention overcomes drawbacks of prior vehicle tracking and communication systems by incorporating in one communication signal simultaneous transmission of voice and data. The system simultaneously transmits voice and data by filtering out a narrow notch of the voice signal centered at a desired frequency, such as, for example, 2500 Hz. The digital signal processor then shapes the mobile unit data to fit within the notch at 2500 Hz in the voice signal. The two signals combine to create the single signal sent out over the cellular telephone network. The combined signal generally mirrors the original voice signal. This feature makes the present invention compatible with any cellular, radio, microwave, or telephone system. This is a significant advantage over systems of the prior art, which require special telephone system configurations to operate. A separate wideband data mode, wherein voice communication is suspended, is also provided. In one embodiment, the data channel provided in the combined data/voice mode is used as a control channel to initiate the wideband mode.
A processor in the mobile unit provides low-power mode of operation by shutting down various portions of the mobile unit (such as the GPS receiver and the cellular transmitter) to conserve power. In one embodiment, power-up from the low power mode is provided by a variable wake-up window feature.
In one embodiment, the mobile unit, while in low power mode, listens to radio frequencies in a pager frequency band. The monitoring station tells the mobile unit to power-up by sending a message to the mobile unit using the pager frequency band.
Upon reception by a receiving unit, the signal is again filtered to separate the data information from the voice information. The voice information, although missing a small amount of voice information at 2500 Hz, does not noticeably suffer from signal degradation because the amount of data removed from the voice signal is insignificant. Further, the 2500 Hz frequency at which this notch occurs is chosen to minimize degradation of the voice signal""s quality.
Further enhancing the operation of the present invention is continual transmission of GPS location data. Continual transmission of the GPS location data to the monitoring station allows a technician at the monitoring station to continually track on a digitized map the movement, in real time, of the vehicle. Continual transmission of the GPS location data is achieved, in part, because of the novel method of packaging the GPS location data sent over the telephone network.
Advantageously, the present invention arranges the data signal differently then most modem communication configurations. Generally, communication by modem incorporates introductory preamble and synchronization information to synchronize the relationally larger amounts of data passing between the sending and receiving devices. However, in the present invention, small but continual bursts of GPS data are sent. The communication device of the present invention disposes with the preamble and the synchronization information and instead begins by sending packets or payloads of mobile unit data. After receiving a packet, the signal processor synchronizes and demodulates the information. This method reduces the time and bandwidth requirements for sending small payloads of information and thereby improves the quality of the received voice signal.
The present invention also overcomes the complications resulting from echo introduced by telephone service providers. The echo is undesirable when sending voice and data simultaneously, as in the present invention. The present invention overcomes this hurdle through the use of an interrupt detector in the mobile unit and the monitoring station. The interrupt detector synchronizes data transmission to briefly cease transmission from the mobile unit if the monitoring station needs to send a brief activation signal to the vehicle""s remote operation devices. This feature overcomes the disruption of data caused by telephone system echo.
Another important advantage is that it provides a monitor on the unattended automobile without requiring a substantially disabling draw on the automobile battery. As described below, the preferred embodiment includes a xe2x80x9csleepxe2x80x9d mode with a negligible current drain. Periodically, the system is momentarily xe2x80x9cwakenedxe2x80x9d to determine if any intervention activity has occurred so that an alarm message is automatically sent from the vehicle to the monitoring center.
Further objects, features, and advantages of the present invention over the prior art will become apparent from the detailed description that follows, when considered with the attached figures.